RU2610084C2 - Vapour generation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: hydrocarbons extraction equipment comprising: a well passing from the surface to the hydrocarbon containing formation. Vapour generation devide (10) is located in the well and designed to generate vapour from fluid. The device comprises a fluid circulation pipe (12) containing an electrically and thermally conductive material, and at least one inductive cable (14) made of electrically conductive material wound around the fluid circulation pipe. Wherein, the fluid circulation pipe is configured to generate partly enclosed area with an internal pressure. Hydrocarbons extraction equipment is adapted to control the internal pressure the fluid is exposed to during heating. Also a hydrocarbons extraction method is proposed.

EFFECT: improved vapour generation.

16 cl, 5 dwg

Description

This invention relates to steam generation, and more particularly to a device and method for generating steam.

Steam generation is used in many areas of industry, in particular, in the production of hydrocarbons. For example, when producing viscous oil, heavy or not, it may be necessary to dilute the oil (i.e., lower the viscosity of the oil) before recovering. Such liquefaction is even more useful for heavy oil contained in sands, for example in asphalt sands (found, in particular, in Canada and Venezuela). However, a decrease in the viscosity of oil is obtained, as a rule, by using thermal energy. For this, steam injection into the formation is widely used.

Various steam injection methods are currently being used (e.g., stimulation by cyclic steam injection (CCS), steam displacement, steam gravity drainage (SAGD)). Steam generation is usually carried out on the surface using special plants or various types of steam generators. After that, the steam is transferred into the reservoir through a pipe partially located on the surface. Thus, these steam generators need a certain service area, which complicates the placement of production equipment. For example, it can be difficult to install additional steam generators on small offshore drilling platforms. In addition, surface steam generation causes heat loss in parts of the pipe located on the surface and in the well. Heat loss in the well leads to heating of the area adjacent to the well, and not just the formation (which is usually located at the bottom of the well). These heat losses are a particular problem if a well passes through permafrost. Heat losses impair steam quality. Typically, heat loss causes a reduction in well depth. Surface steam generators usually run on fossil fuels (gas, recirculated portion of the produced oil). The heat losses mentioned above reduce the efficiency of the steam injection unit.

WO 1988/000276 A1 discloses a heat generator for oil wells, comprising an elongated chamber in which a pair of non-concentric electrodes are located at least partially immersed in water. During operation, electricity is supplied to the electrodes and they heat the water. However, the generator disclosed in this document, in light of the above-mentioned disadvantages, is not entirely satisfactory.

In addition, in some documents, for example in EP 0387125 and GB 427838, it is proposed to heat a fluid flowing through a pipe forming a secondary circuit of an electric transformer. These transformers use a closed ferromagnetic core. For example, a primary circuit (supplied with electricity) is wound around a first branch, and a secondary circuit (formed by a pipe) is wound around a branch parallel to the first branch. As a result, two of the three overall dimensions (height, width and length) of the devices described in these documents turn out to be too large so that, at a certain flow rate of the generated steam, the devices could be introduced into the well. Therefore, they are not optimal for use in oil wells.

The objective of the invention is to provide an improved device and method for generating steam, at least partially devoid of the above disadvantages.

To this end, the present invention relates to a steam generation device. The device comprises a pipe for circulating a fluid containing electrically conductive and thermally conductive material, and at least one inductive cable made of electrically conductive material and wound around the pipe.

The present invention also relates to a method for generating steam by means of a steam generation device. The method comprises circulating water in the pipe and, at the same time, supplying electricity to the inductive cable.

The present invention also relates to a method for producing hydrocarbons comprising generating steam according to a method for generating steam.

The present invention also relates to hydrocarbon production equipment comprising a steam generation device.

According to preferred embodiments, the invention contains one or more of the following features:

- the pipe has at least one protrusion on the inner wall;

- the pipe is cylindrical;

- the protrusion is a trapezoid, located in a spiral along the pipe;

- the trapezoid is continuous or intermittent;

- the device also contains a sheath made of a ferromagnetic material located around the inductive cable;

- the inductive cable forms a solenoid;

- the inductive cable is hollow;

- the pipe has a diameter of less than 20 cm, preferably less than 15 cm;

- the pipe has a length of less than 30 m, preferably less than 20 m, and / or more than 5 m, preferably more than 10 m;

- the device also contains a source of electricity supplied to the cable;

- a power source supplies a current of more than 500 A, preferably more than 900 A;

- the device contains several pipes for the circulation of water connected to each other.

Other features and advantages of the invention are apparent from the following description of one preferred embodiment of the invention, provided by way of example, with reference to the accompanying drawings, in which:

figure 1 illustrates an example of a method of generating steam;

figure 2 and 3 shows an example of a device for generating steam;

figure 4 shows an example of a receiver;

5 shows an example of magnetic field lines in a steam generation device.

A steam generation device is proposed. The device comprises a pipe for circulating a fluid containing electrically conductive and thermally conductive material, and at least one inductive cable made of electrically conductive material and wound around the pipe. Such a device improves steam generation.

The water circulation pipe allows water to circulate in a direction from the pipe inlet to the pipe outlet. The pipe contains an electrically conductive material, such as steel. It can be fully or partially made of the aforementioned electrically conductive (i.e., capable of conducting electricity) and heat-conducting (i.e., capable of efficiently conducting heat) material. The inductive cable is made of electrically conductive material and, thus, is an electric cable made, for example, of copper. Inductive cable can be of any shape. For example, an inductive cable may have a square cross section. The cable cross section may be greater than 9 mm ² , preferably greater than 36 mm ² , and / or less than 144 mm ² , preferably less than 64 mm ² .

Since the inductive cable is wound, it has turns. Accordingly, an inductive cable can induce a strong magnetic field inside said turns, provided that electric power is supplied to the inductive cable. The electrically conductive material of the pipe allows the generation of Foucault currents when exposed to a given magnetic field. Thus, under the influence of this magnetic field, Foucault currents heat the pipe due to the Joule thermal effect and transfer thermal energy to the fluid that may be present in the pipe so that steam formation is possible. The inductive cable is wound around the pipe and, thus, provides the possibility of a magnetic field in the place where the inductive cable is wound around the pipe. One advantage of this arrangement is also the length of the pipe useful for heating. In fact, heating takes place along the entire length of the winding of the inductive cable around the pipe, and it occurs gradually as the fluid circulates in the pipe. Such a device provides high efficiency (output) and, accordingly, high-quality evaporation of water (if the fluid is water). Steam quality is the ratio between the amount of water in the form of saturated steam and the total amount of water (i.e. liquid plus saturated steam). In addition, the elongated shape of the device makes it particularly suitable for use in oil wells. Indeed, the device is easily inserted into the well. Such a device also makes it possible to obtain a straight flow, as well as more effectively maintain the inlet pressure.

Inductive cable can form a solenoid. In particular, the inductive cable can form a coil, the length of which is at least two times the diameter of the coil. This allows you to create a powerful magnetic field near the pipe and, accordingly, to provide a high thermal effect of the Joule. Preferably, the inductive cable is wound around the pipe in a section whose length is more than 50 times the diameter of the pipe, preferably more than 200 times the diameter of the pipe, which allows heating a large section of the pipe along its length.

The device may include a sheath made of a ferromagnetic material and located around the inductive cable. The shell directs the magnetic field to optimize heating. In addition, if the device is inserted into the casing (i.e., a metal pipe cemented to the wall of the well), the casing protects the casing from magnetic flux. The ferromagnetic shell material may be soft iron or any other material having the characteristics of a soft ferromagnetic material.

The pipe may have at least one protrusion on the inner wall. Hereinafter, the term “receiver” means a protrusion or all protrusions, if any. The receiver may be a portion of the pipe protruding inside the pipe. The receiver increases the inner surface of the pipe and creates hot spots (the temperature of which can exceed 300 ° C and range, for example, from 350 to 400 ° C). Accordingly, the receiver improves the heating of the fluid in the pipe. In addition, the receiver creates turbulence during the circulation of the fluid. Turbulence generates currents that homogenize the fluid and thus distribute heat to improve heating quality. The receiver also causes pressure loss (i.e., local pressure loss), favoring steam generation.

Receivers can be of various shapes. To improve heating, the receiver can form a trapezoid, which is located in a spiral along the pipe, which may be cylindrical. The trapezoid can be continuous or intermittent. If the trapezoid is discontinuous, the receiver contains several protrusions located on an imaginary spiral line inside the pipe.

Inductive cable may be hollow. In this case, the cable contains free passage in its center. This passage allows coolant, such as water, to circulate inside the inductive cable, thereby avoiding damage to the inductive cable. Inductive cable cooling can also serve to pre-heat evaporated water. For example, the passage in the inductive cable can be connected to the pipe upstream of the pipe. As a result, regardless of the method of generating steam using the device, water can circulate in the inductive cable before entering, in a preheated form, into a pipe where it will be easier to evaporate water.

The pipe may have a (outer) diameter of less than 20 cm, preferably less than 15 cm. The casing of the well has a diameter of approximately 30 cm. The internal diameter of the pipe may be less than 16 cm, preferably less than 10 cm. Thus, the dimensions of the pipe provide space for winding inductive cable around the pipe. Accordingly, the device is well suited for commonly used wellbore diameters, i.e. 23-25 cm.

The pipe may have a length of less than 13 m, preferably less than 10 m, and / or more than 5 m, preferably 8 m, preferably equal to or at least approximately 9 m. These dimensions are a good compromise between ease of installation and usable length used. In fact, the longer the pipe, the more heat can be provided over a long section of the pipe. The length of the sections, however, is limited to better adapt to standard drilling rigs (i.e., drilling equipment).

In addition, the device may contain a source of electricity supplied to the inductive cable. The power source may be located on the surface and transmit electricity to the winding of the inductive cable / cables around the pipe / pipes (in the well in the formation) through one or more transmission cables. Such a steam generator can operate without fossil energy. It cannot generate gases causing the greenhouse effect, in any case, in excessively concentrated quantities. Therefore, such a steam generator is environmentally safer and has a high efficiency, since electricity is easily transmitted at low frequencies with less transmission loss. Such a device contributes to an increase in steam output since there is no heat loss. In fact, steam is generated directly in the well, closer to the formation than to the wellhead, and is not transferred from the surface.

The electric power supplied to the cable may be an electric current with a force of more than 500 A, preferably more than 900 A. To reduce losses at this current strength, the device preferably contains several transmission cables. In this case, the power source is adapted to provide the appropriate voltage. The range of permissible voltages can be from 5 to 10 kV.

The pipe can also be a partially enclosed space, the pressure inside which the pressure of the formation is little affected. This allows you to control the pressure that the fluid undergoes during heating. Thus, it is possible to easily determine the characteristics of the generated steam (if the fluid is water) and to effectively control the generation of steam over an extended period of time. The dimensions of the invention are a function of the characteristics of the formation, in particular the vapor pressure supplied by the system according to the invention is higher than the pressure of the formation to be developed.

The device may contain several pipes for the circulation of water connected to each other. Pipes can be connected to each other with the possibility of transferring fluid through mechanical connections for the subsequent circulation of water inside all pipes. Cables wound around pipes are connected by electrical connections. It is possible, for example, to connect three pipes to each other.

The device may be contained in hydrocarbon production equipment. The device, in particular, can be located in the well so that steam is generated directly at the formation. This makes the equipment compact and allows for the development of any high-viscosity hydrocarbon fields, which is due to the quality of the generated steam, the ability to control the characteristics of the generated steam and the compactness of the equipment, which, in particular, makes it possible to use this equipment on offshore drilling platforms.

Production equipment may include a drilling rig. In this case, the location of the device may contain:

- positioning the pipe, with at least one electrical cable wound, in a drilling rig;

- lowering the pipe into the well, while access to the top of the pipe remains from the rig;

- positioning of a new pipe in a drilling rig;

- connecting a new pipe, with at least one electric cable wound, to a previous pipe, comprising connecting a cable of a new pipe to a cable of a previous pipe;

moreover, the above steps are repeated until, for example, three pipes are connected to each other.

As shown in FIG. 1, the device can be used in a steam generation method comprising circulating (S1) water in a pipe and, at the same time, supplying electric power (S2) to the cable. The electric energy of the cable induces a magnetic field, heating the electrically conductive material of the pipe and heating the water circulating in the pipe to the evaporation temperature, simultaneously with the supply of electricity. Such a device, respectively, provides the evaporation of water with high efficiency and high quality steam.

As mentioned above, water can be preheated. To this end, the method may comprise pre-circulating water in the cable to cool it.

This method may be contained in a hydrocarbon production method. Steam generation can be carried out directly at the formation, and therefore, it can be injected directly into the formation without heat loss. This simplifies the extraction of hydrocarbons, which is especially important in the case of the production of viscous or heavy oil.

According to this method, steam can be generated in an amount of 100-300 tons per day, preferably 200 tons per day. The hydrocarbon production method can be carried out by cyclic injection of steam into the formation (H&P, Huff & Puff) or by steam displacement, that is, continuous washing of the formation with steam (Steam Drive). The same device can provide steam injection in both of the above modes. Thus, the device is universal.

Further, embodiments of the device are described with reference to FIGS. 2-5. Figure 2 shows one example of a device 10 for generating steam in longitudinal section. In Fig. 2, device 10 is shown together with a pipe 12 for circulating a fluid containing electrically conductive and thermally conductive material, as well as an induction cable 14 made of electrically conductive material and wound around pipe 12. Fig. 3 shows a section of the device 10 shown in .2 perpendicular to the longitudinal central axis 22 of device 10 and comprising a portion 29 of pipe 12 around which an inductive cable 14 is wound.

As shown in the drawings, liquid water 16 can penetrate into the pipe 12, circulate in it and leave it in the form of steam (the liquid content in it is a function of the achieved quality). The cable 14 is supplied with electric voltage from the electric power source 19, and the cable heats the pipe 12 by means of a magnetic field induced over the entire length of the winding. In this example, the device 10 contains transmission cables 24, through which electricity is supplied to the cable 14, and a receiver 20 located on the inner wall of the pipe 12 (protrusions directed inside the pipe 12, that is, to the axis 22). Thus, a high thermal efficiency is achieved. As a result, the evaporation of water 16. As shown in the drawings, the device 10 is compact and has an elongated shape. The length of the device 10 is at least two times its width. Accordingly, the device 10, which does not have a large volume, is suitable for input into the well.

In addition, the device may contain several pipes (three pipes) connected to each other by means of connections and forming a pipe with a total length of 29 m (for example, 27 m), around which a cable 14 is wound, the length of each of the pipes 12 around which it is wound cable 14 is 9 m. Also shown is a device 10 installed inside the well. As, in particular, shown in the drawings, the casing 23 of the well is surrounded by cement 13. Near the cable 14, the geological soil contains hydrocarbons and thus forms a formation 25. Thus, the location of the pipes 12 around which the cable 14 is wound in the formation avoids heat loss. Due to this, useless heating of part 26 of the underlying soil layer that is closest to surface 15 and does not contain hydrocarbons does not occur. The drawings also show a sheath 27 protecting the casing 23 from too high temperatures.

Figure 4 shows the receiver 50 in the form of a spiral trapezoid in the pipe 12, which can be used in the device 10 shown in figure 2 and 3. In the cross section of the pipe 12 shown in figure 4, located in the plane of the section of the receiver 50 has the form of protrusions located at the same distance from each other. The receiver 50 can be made of electrically conductive and thermally conductive material, which will increase the surface of the heat exchange with the fluid, as shown in the drawing.

5 schematically shows an example of a graphical representation of magnetic field lines 40 in one embodiment of a steam generation device 10. The magnetic field lines 40 are obtained using software developed for finite element calculations. The device is partially shown in longitudinal section. Only half of the device is shown. The device shown in this example corresponds to FIGS. 2 and 3 and, in particular, comprises a sheath 27 around the cable 14. As shown in the drawing, the sheath 27 allows the magnetic field to be concentrated on the pipe 12 and to protect the casing 23, to some extent also exposed to magnetic fields. The device 10 allows to achieve a good Joule effect for heating the pipe 12 with less damage to the casing 23.

Obviously, this invention is in no way limited to the described and illustrated embodiments of the invention and may contain any alternatives known to those skilled in the art.

Claims (43)

1. Equipment for the production of hydrocarbons intended for the production of hydrocarbons from a hydrocarbon containing formation, wherein the equipment for the production of hydrocarbons contains: - a well extending from the surface to a hydrocarbon containing formation; - a device (10) for generating steam located in the well and designed to generate steam from a fluid, the device comprising: - a pipe (12) for circulating a fluid containing electrically conductive and thermally conductive material; and - at least one inductive cable (14) made of an electrically conductive material and wound around a pipe for circulating fluid; moreover, the pipe for circulating the fluid is configured to form a partially enclosed space with internal pressure; wherein the hydrocarbon production equipment is configured to control the internal pressure to which the fluid is exposed when heated. 2. Equipment for the production of hydrocarbons according to claim 1, in which the pipe for circulating the fluid has at least one protrusion (50) on the inner wall. 3. The hydrocarbon production equipment according to claim 2, wherein the pipe for circulating the fluid is cylindrical and the protrusion is a trapezoid arranged in a spiral along the pipe for circulating fluid. 4. Equipment for the production of hydrocarbons according to claim 3, in which the trapezoid is continuous or intermittent. 5. Equipment for the production of hydrocarbons according to claim 1, wherein the device also comprises a sheath (27) made of a ferromagnetic material and located around the inductive cable. 6. Equipment for the production of hydrocarbons according to claim 1, in which the inductive cable forms a solenoid. 7. Equipment for the production of hydrocarbons according to claim 1, in which the inductive cable is hollow. 8. The hydrocarbon production equipment of claim 1, wherein the pipe for circulating the fluid has a diameter of less than 20 cm, preferably less than 15 cm. 9. The hydrocarbon production equipment according to claim 1, wherein the fluid circulation pipe has a length of less than 30 m, preferably less than 20 m, and / or more than 5 m, preferably more than 10 m. 10. Equipment for the production of hydrocarbons according to claim 1, in which the device also contains a source (19) of electricity supplied to the cable. 11. The hydrocarbon production equipment of claim 10, wherein the electric power source delivers a current of more than 500 A, preferably more than 900 A. 12. Equipment for the production of hydrocarbons according to claim 1, in which the device contains several pipes for the circulation of water connected to each other. 13. A method for producing hydrocarbons, the method comprising generating steam according to a method for generating steam, wherein the method for generating steam comprises: - ensuring the availability of equipment for hydrocarbon production, intended for the production of hydrocarbons from a hydrocarbon containing formation, and equipment for the production of hydrocarbons contains: - a well extending from the surface to a hydrocarbon containing formation; - a device (10) for generating steam located in the well and designed to generate steam from a fluid, the device comprising: - a pipe (12) for circulating a fluid containing electrically conductive and thermally conductive material; and - at least one inductive cable (14) made of an electrically conductive material and wound around a pipe for circulating fluid; moreover, the pipe for circulating the fluid is configured to form a partially enclosed space with internal pressure; wherein the hydrocarbon production equipment is configured to control the internal pressure to which the fluid is subjected when heated; - circulation (S1) of water in the pipe for circulation of the fluid; and at the same time - supply (S2) of electricity to the cable; - injection into the reservoir of steam generated by the steam generation device. 14. The hydrocarbon production method according to claim 13, wherein the steam generating device of the hydrocarbon production equipment generates steam in an amount of 100-300 tons per day. 15. The hydrocarbon production method according to claim 14, wherein the steam generating device of the hydrocarbon production equipment generates 200 tons of steam per day. 16. A method of arranging hydrocarbon production equipment for producing hydrocarbons from a hydrocarbon containing formation, the hydrocarbon production equipment comprising: - a well extending from the surface to a hydrocarbon containing formation; - a device (10) for generating steam located in the well and designed to generate steam from a fluid, the device comprising: - a pipe (12) for circulating a fluid containing electrically conductive and thermally conductive material; and - at least one inductive cable (14) made of an electrically conductive material and wound around a pipe for circulating fluid; moreover, the pipe for circulating the fluid is configured to form a partially enclosed space with internal pressure; wherein the hydrocarbon production equipment is configured to control the internal pressure to which the fluid is subjected when heated; moreover, the method comprises the following steps: - positioning the first pipe for circulating fluid with at least one electrical cable wound around it in a drilling rig; - lowering the first pipe for circulating fluid into the well, while access to the upper part of the first pipe for circulating fluid remains from the rig; - positioning a second pipe for circulating fluid with at least one electric cable wound around it in a drilling rig; a connection of a first pipe for circulating a fluid with a second pipe for circulating a fluid, comprising an electrical connection of an inductive cable of a first pipe for circulating a fluid with an inductive cable of a second pipe for circulating a fluid.

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